Toe Rail Tough Enough For Preventer?

[unbusted67]

I have a cal 35 with an aluminum toe rail I am wondering if it is stout enough to run a preventer to? I am planning on detaching the boom gang from the base of the mast and running it to the toe rail between the lifelines.

[Vasco]

Is the toe rail through bolted? If it is I would not worry about taking the vang to it.

[Dennis.G]

Likely OK if you run preventer from end of boom, but if you use the vang as a preventer to the toe rail you end up with a lot of leverage from boom should you back-wind the main, with a much higher strain at the toe rail.

[SkiprJohn]

Do you have a photo of your toerail? Is it throughbolted with backing plates? Your vang attaches to mid point on your boom, correct? If your boom dips into the water will your boom bend in the center and break?
I suppose on a gorgeous sailing day with 12 knots of wind and light seas it would be ok but not for a permanent solution. Best solution would be to run your preventer from the end of the boom to your bow cleat.

kind regards,

[casual]

If thru bolted on my C&C 36 it was,I,ran the preventer there also tacked the Geneker to the toe rail on the bow.

[islandplanet]

Some guys will rig a preventer with a "fuse", a lighter piece of line designed to give if there's a big load that might break the boom. Most toerails will be strong enough for attachment if the fasteners have something backing them, which I'd expect to the case on your Cal.

[SkiprJohn]

Credit to Sailboatdata.com.

CAL 35 (1979) sailboat specifications and details on sailboatdata.com

Is this the same as your boat? If so, I'd consider what I posted earlier. Vang attachment is pretty far forward to act as a preventer.

kind regards,

[Andrew Troup]

I came across this expired thread accidentally while I was responding to the same question from an email correspondent, so I thought I'd copy it to the forum:

Generously proportioned toerails are certainly strong enough for preventer service if well installed, but you wouldn't want to rely on a single slot, I reckon

.... and certainly not via a shackle !

Here's a loadsharing setup which lasted a few trips: the problem was that the sharp corners of the punched apertures in the toerail had not been lovingly hand-finished ( say with a flap-wheel in a die-grinder) prior to anodising. We were reluctant to do so afterwards, because the webbing becomes a veritable salt-mine, and poultice corrosion a real possibility.

The trouble is that load sharing requires movement, which is death where sharp edges are concerned.


This toerail preventer effortlessly coped with a couple of accidental gybes with much too much sail up, the first night of the maiden circumnavigation.

These came about when the helmsman (unused to wheel steering, deprived at 0300 from visual references by the sudden onset of a vigorous cold front straight from Antarctica, and hypnotised by the compass card nutating around the bowl like an erotic dancer) became seriously disoriented, and took the bow on a package tour of the horizon.

The second gybe 'compromised' the Lewmar 100mm ratchet blocks on the boom, spewing balls over the deck. Once these were replaced by same sized Lewmar "Ocean" series, plain bearing blocks, no further problems have been experienced.

He left the boat prematurely at the next port, despite it being the back of beyond and beyond the reach of any transport network, claiming he'd remembered an important meeting he had to attend, and assuring us, not very convincingly, he'd had a 'wonderful time' (probably muttering under his breath the famous Groucho Marx followup line: "but this wasn't it")

As we knew it would, the webbing started to cut through within months, and we came up with a more thoughtful setup.

The single sling shown was replaced with three separate webbing slings (each a single endless loop), made with 'beer knots', and then each cow-hitched through an adjacent slot.

The lengths of the loops were graduated, so all would end at a common point when pulled from the direction of the loaded preventer. The shortest loop was the minimum possible length, to keep the whole thing compact.

The end of the preventer was tied through all three at once, after laying them neatly in a club-sandwich stack, using a double sheetbend.

That kludge has lasted a decade, round NZ a few times and multiple trips to the Pacific and back.

Cow hitches rock ! (and beer knots rule!)

[sww914]

It usually is but I do have a friend with a catamaran that ripped three feet off when he let the preventer get loose and let the wind get on the wrong side of the main suddenly. It turned into an expensive uncontrolled gybe.

[Andrew Troup]

Good point.

A loose preventer should never be cleated: it's the worst of all possible situations.

[unbusted67]

I love this and will be stealing your idea promptly. I have a few questions though. Is the picture below a picture of the successful 10 year setup or the one that wore through?

I'm also a little confused about this part:

"The lengths of the loops were graduated, so all would end at a common point when pulled from the direction of the loaded preventer. The shortest loop was the minimum possible length, to keep the whole thing compact.

The end of the preventer was tied through all three at once, after laying them neatly in a club-sandwich stack, using a double sheet bend."

What is graduated other than what high schoolers do? And what is a club sandwich stack?

Originally Posted by Andrew Troup

I came across this expired thread accidentally while I was responding to the same question from an email correspondent, so I thought I'd copy it to the forum:

Generously proportioned toerails are certainly strong enough for preventer service if well installed, but you wouldn't want to rely on a single slot, I reckon

.... and certainly not via a shackle !

Here's a loadsharing setup which lasted a few trips: the problem was that the sharp corners of the punched apertures in the toerail had not been lovingly hand-finished ( say with a flap-wheel in a die-grinder) prior to anodising. We were reluctant to do so afterwards, because the webbing becomes a veritable salt-mine, and poultice corrosion a real possibility.

The trouble is that load sharing requires movement, which is death where sharp edges are concerned.


This toerail preventer effortlessly coped with a couple of accidental gybes with much too much sail up, the first night of the maiden circumnavigation.

These came about when the helmsman (unused to wheel steering, deprived at 0300 from visual references by the sudden onset of a vigorous cold front straight from Antarctica, and hypnotised by the compass card nutating around the bowl like an erotic dancer) became seriously disoriented, and took the bow on a package tour of the horizon.

The second gybe 'compromised' the Lewmar 100mm ratchet blocks on the boom, spewing balls over the deck. Once these were replaced by same sized Lewmar "Ocean" series, plain bearing blocks, no further problems have been experienced.

He left the boat prematurely at the next port, despite it being the back of beyond and beyond the reach of any transport network, claiming he'd remembered an important meeting he had to attend, and assuring us, not very convincingly, he'd had a 'wonderful time' (probably muttering under his breath the famous Groucho Marx followup line: "but this wasn't it")

As we knew it would, the webbing started to cut through within months, and we came up with a more thoughtful setup.

The single sling shown was replaced with three separate webbing slings (each a single endless loop), made with 'beer knots', and then each cow-hitched through an adjacent slot.

The lengths of the loops were graduated, so all would end at a common point when pulled from the direction of the loaded preventer. The shortest loop was the minimum possible length, to keep the whole thing compact.

The end of the preventer was tied through all three at once, after laying them neatly in a club-sandwich stack, using a double sheetbend.

That kludge has lasted a decade, round NZ a few times and multiple trips to the Pacific and back.

Cow hitches rock ! (and beer knots rule!)

[Andrew Troup]

Sorry, I'll try again.

I don't think I've got a close up photo of the current setup. The one shown above was the one which wore through quickly. It's a single sling or strop, laced through the toerail and the stainless ring.

This is great in theory because the tensions in each 'leg' (webbing between ring and rail) are automatically equalised, regardless of the direction of pull.

However in practice, mainly because the slots in the toerail are 'as punched'

By that I mean: if you sawed off a short length section of toerail, cutting through a slot, you'd see 90 deg corners, not radiused ....

Because of this scraping edge, it's not viable to have any movement of the webbing as the loads change magnitude and direction.

So the second idea used three individual slings on each toerail, one through each slot. They were 'graduated' in length, meaning the length varied from shortest at the front to tallest at the back.

(I guess you 'graduate' from school when you attain a sufficient intellectual -- or, failing that, physical -- stature !)

Each sling is "endless", either sewn, as a sailmaker or harness maker would do, or beer-knotted, like a mountain climber's or caver's sling.

They're all cow-hitched through the toe rail, then one at a time (starting with the short one) cow-hitched through the ring. The last one was not, IIRC, the easiest.

(I think I misremembered in my previous post about laying the three eyes stacked on top of each others, like a layer cake or 'club sandwich' - and simply tying through them, because there is definitely still a ring for the turning block to shackle to.)

It was 10 years ago, so I'm sorry I can't remember the grisly details. I do seem to remember it took a couple of tries to get the port side right, but then I was able to just copy it to starboard.

The length of the shortest sling needs to be as short as you can make it and still get all the hitches on.

If your toerail apertures have been nicely radiused, or it's not anodised (meaning you can radius the applicable slots), the load-sharing version shown in the photo would probably be fine.

[donradcliffe]

Just remember that you want the preventer to be the weak link and fail before the toe rail or the boom. Size it accordingly.

[Andrew Troup]

Originally Posted by donradcliffe

Just remember that you want the preventer to be the weak link and fail before the toe rail or the boom. Size it accordingly.

I strenuously beg to differ. A broken preventer is a nightmare, arguably more hazardous than a broken boom in some situations, certainly more hazardous (at the instant it breaks) than a broken toerail. The stored energy is colossal, like firing a loaded crossbow.

Whereas easing a preventer, even with the main aback in 40 knots or more, is like unloading a crossbow using the winch provided.

If you feel the need for a failure point, I recommend a progressive fuse. The neatest way is to make or buy some sort of progressive-tear shock absorber (try googling "Via Ferrata" and look for that term) or a 'graduated' (that word again!) series of increasingly strong, increasingly long lashings, discussed on other threads on this forum.

Probably a google search on:

fuse preventer site:cruisersforum.com

would bring up some suggestions.

Ideally the boom ends up being arrested by the time it's starting to come over the toerail level with the front of the cockpit. At this point it's no longer putting the rig at risk, but stops short of putting the crew at risk.

[Andrew Troup]

I should add that it's a fair point Don raises: a toerail preventer is not something to be installed lightly. If your boat has any potential to dip the boom (long and/or low boom, narrow beam, rolly boat, whatever) then an end-of-boom to bow preventer is a safer option.

And if your boom is skinny in relation to the size of the main: in other words, if you would not be happy to shift the mainsheet to where the vang is, then you'll need to reinforce (or possibly bridle) the boom.